In a dispensing apparatus of this kind (see, for example, EP-A 0 252 401, U.S. Pat. Application Ser. No. 070,033, now U.S. Pat. No. 4,826,053) the two dispensing plungers are arranged side-by-side in the apparatus, and the slide-in opening of the retaining guide is located at the upper edge of the apparatus front. Consequently, the double cartridges with their essentially rectangular holding flanges are slid into the guide from above, and the flange is then held at the lower longitudinal side and the two lateral narrow sides while the upper longitudinal side of the flange remains free. Due to the relatively wide slide-in opening, it must accept at least the diameters of both storage cylinders of the double cartridges being adjacent to each other. Solid anchoring of the cartridge of the dispensing apparatus, however, is simply not achieved. It must also be taken into consideration that this anchoring is subjected to considerable stresses during dispensing of the substance when the plungers act upon the delivery pistons in the cartridge cylinders. This causes bending of the flange and deformations of the cartridge, which can lead to disturbances in material dispensing; during step-wise dispensing, the elastic bending leads to undesirable no-load strokes during each plunger advance and subsequently impairs, due to spring-back resilience, the immediate relief of the delivery piston as was suggested in the above mentioned published application.
This anchoring turns out to be insufficient especially if the two cartridge cylinders are separated longitudinally from each other, i.e. are connected with each other practically only through the holding flange and in the region of the outlet. Some degree of improvement--if any can be achieved at all--is only possible in the known apparatus design by thickening or reinforcing (ribbing) the cartridge holding flange. This, however, raises the material and production costs for the cartridges, which is extremely undesirable for such disposable parts intended for a one-time use.
The present invention is based on the task of achieving rigid anchoring, which can be subjected to high stress, between dispensing apparatus and exchangeable cartridges through suitable apparatus design and without increased costs for the cartridges.